first, if they have a meat department they will almost certainly have bones for sale. ask at the counter, ask for soup or stock bones, they will know what you mean. and of course you want good organic ones.
yes, you can use chicken bones. first cook the chicken as you normally would. you cna freeze the chicken if its too much to eat at that time. clean the bones as best you can, the cleaner the bone the better. then put them in a pot with water. i use a crock pot, that way i can let it steep while i am gone. you can let it steep for 24 hours or more. add a splash of acv to draw the minerals out of the bones. first bring to a boil, then simmer.
after a while the bones get soft and you can then cut them open to expose the marrow to the broth. the marrow is where the REALLY good stuff is. i put a large knife on along the long edge of the bone, then hit it wiht a hammer. it takes one or two blows, the bone is quite soft after cooking for an hour or two. once te bone is split, put it back in the broth and cook for longer.
if you buy the bones from the butcher, ask if they can cut the bone for you, they often will. ask that they cut the bone so the marrow is exposed. this is an ancient secret of cultures like china and the jewish people, they know how much goodness lies in the marrow.
once the stock is done, you can drink it plain, add molasses, or make any kind of soup you like with it. i make curry soup with veggies like garlic and greens, its absolutely delish.